Sundsvall Energi in Sweden

Waste-to-energy plant, CHP

We signed the contract for Sundsvall Energi’s new waste-to-energy plant on 30 June, 2004 and the plant officially opened in March 2007.

The new plant has a capacity of 25 tonnes of waste/hour, corresponding to an annual operation of 200,000 tonnes and it is located next to the old plant.

It produces approximately 120,000 MW electricity and 300,000 MW district heating.

Sundsvall Energi by night. Photo: Torbjörn Bergkvist

Scope of supply

We supplied the grate and boiler.The combustion grate is DynaGrate®, a two-lane air-cooled and water-cooled grate, designed for fuels with high heating values.

The water-cooled DynaGrate® - the new generation

The water-cooled DynaGrate® is the new generation of the grate. It provides the same process and mechanical advantages as the air-cooled version. Furthermore, it has the advantage of lower maintenance cost, reduced amount of grate riddling and less problems with molten metal. The primary combustion air can be controlled without consideration for the cooling of the grate bars. Moreover, low excess air results in less flue gases, thereby reducing the stack energy loss.

Integrated cooling system in the shaft of the grate

Standard steam hoses are used for connecting the water from the fixed piping system outside the furnace to the moving shafts. The hoses are placed outside the furnace in order to avoid exposure to hot ashes, molten tin, aluminium, etc. that could damage the hoses. As a result of this design, all types of flexible connections are avoided under the grate. This unique design results in a very reliable water-cooled combustion grate that ensures the annual operating hours.

The Sundsvall waste-fired power plant is the first plant with our new cast water-cooled grate bars.

Boiler design with maximum use of Inconel® for corrosion protection

The boiler is designed with three-vertical passes and horizontal convection part. The maximum use of Inconel® for boiler protection limits the use of refractory.

Plant design data

Process parameters

Vaues

Units

Nominal capacity, waste

20

t/h

Max. continuous capacity

25

t/h

Steam pressure

45

Bar

Steam temperature

420

OC

Feed water temperature

130

OC

Energy input

60

MW, Nominal

Boiler outlet flue gas temperature

180

OC

Flue gas values out of boiler:

CO

75*

Mg/Nm3

TOC

5*

Mg/Nm3

NOx

400**

Mg/Nm3

All values refer to 11% dry O2

*) The CO and TOC values refer to a daily average. The plant limit values comply with the EU directive on waste incineration.

The values are before flue gas cleaning.
The plant limit values complies with the EU directive on waste incineration. Naturally the plant in Sundsvall is equipped with a modern flue gas cleaning system.